[1600] Pancreatic Carcinoma with Concurrent, Autoimmune-Like Chronic Pancreatitis – Clinical Implications.

Xuefeng Zhang, Maria Westerhoff, John Hart, Shu-Yuan Xiao. University of Chicago Medical Center, IL

Background: Autoimmune pancreatitis (AIP) accounts for about 2-6% of idiopathic chronic pancreatitis and is a well-known mimic of pancreatic adenocarcinoma. It is crucial to distinguish AIP from pancreatic carcinoma to avoid unnecessary surgery; however, it remains unclear whether a diagnosis of AIP excludes that of carcinoma. In this study, we investigate the potential incidence of AIP-like changes concurrent with pancreatic carcinoma.
Design: Sixty pancreatectomies for carcinoma that also exhibit chronic pancreatitis were reviewed. Periductal/lobular lymphoplasmacytic infiltration, fibrosis, and ductal obstruction were scored on a scale of 0-3. The presence of granulocytic epithelial lesions, obliterative phlebitis, and germinal centers were also recorded. Immunohistochemistry for IgG4 was performed on cases with features suggestive of AIP and on cases without features of AIP as controls. IgG4+ plasma cells were counted in three HPFs (40x) in each case and an average was calculated.
Results: Eight cases showed features suggestive of AIP as characterized by moderate to severe (scored 2-3/3) periductal lymphoplasmacytic infiltration and/or periductal fibrosis. In five of these, IgG4+ plasma cells were more than 20/HPF (25, 30, 51, 75, 120/HPF respectively). All five cases showed germinal centers, three with granulocytic epithelial lesions, and two with obliterative phlebitis. Overall, 8.3% (5/60) of the reviewed cases were found to have histologic and immunohistochemical features of AIP. Most control cases had no or scattered IgG4 + plasma cells (median 2/HPF, ranged 0-65/HPF, p<0.05 vs those with features of AIP). Although three control cases exhibited an increased number of IgG4+ plasma cells (23, 26, 65/HPF respectively), no morphological features of AIP were present in these cases.
Conclusions: Features consistent with AIP were observed in 8.3% of pancreatectomy cases containing carcinoma that also showed concurrent chronic pancreatitis. Therefore, the presence of chronic pancreatitis with features consistent with AIP on core biopsy specimens may not completely exclude a coexisting pancreatic carcinoma. Clinical correlation and close follow up is necessary in this scenario. Furthermore, an increased number of IgG4+ plasma cells alone should not be used as a diagnostic criterion for AIP.
Category: Liver & Pancreas

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 204, Wednesday Morning


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